If you're running a solo GPU I would say it isn't worth it anymore - ASICs for scrypt coins are already available and all you'll achieve is increasing your energy costs and possibly run the risk of damaging your GPU. If you have your heart set I'd say check out middlecoin or wafflepool.

Have a look at ipominer.com pool - they show the profitability of the coins they are mining.

If you are running the card in a PC you use for other work then you'll have to keep the Intensity setting a bit lower so wont get max hash, and remember it will still be increasing your electicity consumption compared to not having it mining (possibly as much as 100W). Find out your cost per kWh and plug it into a mining profitabilty calculator, then you will see what your btc/MH/day needs to be to breakeven.

Its not going to pay for itself overnight, but if you have it running in the background the rewards can still accumulate over time and go some way to paying for the card.